Just made an account to say that setting fastcgi_param HTTPS on; in the in-vhost.conf file in docker also saved my bacon. Made all of the URLs https and removed the too many redirects issue and made my whole site show as secure so all my paypal links work
For those who also may be having this issue:
- REQUIRE_HTTPS=false
- APP_URL=https://<actual_url>
then add fastcgi_param HTTPS on; to ./config/nginx/in-vhosts.conf file under locations
this is in the v5 docker container, but likely still relevant